com.xenoamess.commons.as_final_field.AsFinalField Maven / Gradle / Ivy
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/*
* MIT License
*
* Copyright (c) 2019 XenoAmess
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.xenoamess.commons.as_final_field;
import java.lang.annotation.*;
/**
* If the annotation {@code @AsFinalField} is present on the declaration
* of a field A, then field {@code @A} is thought to be AsFinalField.
*
* If a field is AsFinalField, then it must follow the following rules:
*
* 1. It must have an empty value.
*
* Empty value is a certain value that indicate it be empty.
* By default, empty value shall be the original value of this field type in a static field.
* For example, 0 for int, null for Object, etc.
*
* 2. The field shall only be set when its value equals empty value.
*
* This annotation is mainly used when a field shall be final, but it can't.
* For example, lazy build for a singleton factory, or a resource field which shall be final but have to wait after
* some other classes init.
*
* Technically this is now implemented by using AsFinalFieldUtils#asFinalFieldSet to deal with any set of any
* AsFinalField.
*
* @author XenoAmess
* @version 0.6.0
*/
@Documented
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface AsFinalField {
}